Careful, calling it "Drop B" can be misleading...
If you want to get technical, it would be called "Drop D, tuned down 1 1/2 steps," where you're tuning down the whole guitar then de-tuning the top string an additional step.
"Drop B" means you're only de-tuning the low E string, like with Broken Wings, Come to Life, Before Tomorrow Comes, etc.
Straight from the Blackbird tab book:
Coming Home
Drop D tuning, down 1 1/2 steps:
B-F#-B-E-G#-C#
Come To Life
Drop B tuning, down 1/2 step:
Bb-Ab-Db-Gb-Bb-Eb
